Device for positioning vehicles standing on their own wheels in a manner which is suitable for automation and for vehicles of different types

ABSTRACT

In an apparatus for the conveyance and positioning of a vehicle supported on its own wheels along a production line, the vehicle wheels of each vehicle side are assigned conveying systems, for example apron conveyors or drag-chain conveyors, by means of which the vehicles can be moved further on in strokes. So that the vehicles can be positioned and oriented accurately and efficiently in the longitudinal and transverse directions in an automation-compatible and type-flexible way, in each workstation, the two wheel tracks are assigned in each case a prismatic shaped wheel well which can accept variously sized wheels in the same position. The vehicle wheels are supported transversely displaceably therein. Furthermore, a wheel support is arranged at a distance from the wheel wells and can support the wheels of the other vehicle axle likewise so as to be transversely displaceable. The wheel supports cover the various center distances of all the vehicle types occurring in the production line. The same applies to the width of the rolling tracks, the wheel wells and the wheel supports. Each of the wheel wells and the wheel supports has a pair of movably guided centering edges which project above the rolling level of the rolling tracks and which can be laid against mirror-symmetrical sides of the vehicle tires and can be moved by means of a centering mechanism transversely to the conveying direction positively in synchronism and mirror-symmetrically to the center line of the production line.

BACKGROUND AND SUMMARY OF THE INVENTION

This application claims the priority of PCT International ApplicationNo. PCT/EP99/01167, filed Feb. 23, 1999 (23.02.99) and German patentdocument DE 198 09 515.5, filed Mar. 5, 1998 (05.03.98), the disclosuresof which is expressly incorporated by reference herein.

The invention is directed to an apparatus for intermittent conveyanceand positioning of vehicles rolling on their own wheels within aproduction line such as used, for example, in the industrial massproduction of passenger cars.

In the area of final assembly of passenger cars, it is customary afterthe assembly of the chassis (from which moment on the vehicles stand ontheir own wheels) to convey the vehicles through the subsequent assemblyareas by means of apron conveyors or on runners or by means of dragchains. When vehicles are conveyed by means of slat or apron conveyors,they stand with the vehicle wheels on two slat or apron conveyors whichare laid parallel to one another in the floor of the working lineaccording to the gauge of the vehicle wheels, and are driven slowly.Individual aprons or slats can be supported on the bottom via rollers,so that the composite apron or slat structure can easily be movedforward in spite of the load exerted on individual aprons or slats bythe vehicles bearing down on them.

In transport by runners, the vehicles stand with the two left-hand andthe two right-hand wheels on a rail of U-shaped profile which extendsover the entire vehicle length, so as to form the two runners. Theserunners are moved along the working line by apron conveyors laid in thefloor on the right and left or in each case by means of a closely packedsequence of drivable conveying rollers. The advantage of transport byrunners is that the vehicles standing on runners can be offsettransversely or rotated about a vertical axis in correspondingoffsetting devices. The vehicles can therefore be handled moreuniversally, standing on runners, than when they are conveyed directly,standing on their own wheels, by slat or apron conveyors or by dragchains.

In transport by drag chains, the vehicles roll on their own wheelsthrough the production line along rolling tracks, a drag chain or a pairof drag chains being arranged along the rolling track of one side of thevehicle approximately at the interval of a wheel width. The drag chainsare provided with drivers which apply a thrust to a vehicle wheel, andconvey the vehicle through the production line.

The vehicles conveyed by means of these conveying techniques do not cometo a standstill in a defined position at the individual workstations. Inthe area where these conveying techniques are used, positionaltolerances of a specific body point of ±10 to 20 cm in the longitudinaland/or transverse directions must be allowed for. This wide spread inposition is not permissible for tasks which are to be carried out in anautomated and mechanized way and which presuppose a knowledge of theexact actual position in all three positions in space.

So that an exact actual position can be determined when there is such apronounced spread in the position of the vehicles, it would first benecessary to determine the approximate actual position of the vehicle ineach case by means of a preceding measuring step; the vehicle wouldfirst, as it were, have to be “located”. Only then could this befollowed by a more accurate measuring programme with complex sensortechnology in order to determine the exact actual position. Moreover,since fixed or reference points, suitable for the measuring systems usedin this case, on the outer skin of the vehicles vary according to thetype of vehicle and are themselves even subject to some tolerances, inaddition to the outlay in terms of time and investment, there would alsobe a problem, in detecting the actual position of the vehicles at theindividual workstations accurately in each case. The productivity (whichit is, of course, the precise aim to increase by the use of automationtechniques) would be greatly impaired in view of the time spent indetermining the exact actual position. Under some circumstances, thetime gained by automation as compared with manual work, would beeffectively lost by the time spent in detecting the actual position, sothat automation is not worthwhile.

In the assembly areas which precede chassis assembly (and where variousscopes of work are automated and mechanized) at the individualworkstations the vehicle bodies are normally lifted out of the conveyingslides by means of centering cones (which move into body-side referencebores) and a lifting device, and are brought very quickly into a spatialposition exactly defined by means of stops. However, this techniquecannot be transferred to the assembly area following the chassisassembly, since, at this later assembly stage, the vehicle floor nolonger has any facilities, accessible on the underside and exactlydefined spatially, for receiving the vehicles, and the previously freecentering receptacles are built over and/or closed withtype-specifically different components.

One object of the invention is to improve the basic generic apparatus,to the effect that vehicles of different type rolling on their ownwheels can be efficiently and accurately positioned and orientedautomation-compatibly and type-flexibly within a workstation of aproduction line in the conveying direction and transversely thereto. Theterm “accurately” is intended to cover a relatively small tolerancerange in positioning, within which particular work operations can becarried out readily in a mechanized way or in which the vehicle can veryquickly be oriented and fixed mechanically with even greater accuracyvia jack attachment points or similar points on the vehicle by means ofa fixed apparatus within the workstation.

This and other objects and advantages are achieved by the apparatusaccording to the invention, in which the vehicle is positionedlongitudinally and transversely within a workstation by means of thetires. For positioning in the longitudinal direction, a pair ofprismatic wheel wells is provided, in which the vehicle wheels arereceived exactly in position in the longitudinal direction, butfloatingly in the transverse direction. Even in the case of differentwheel sizes occurring in practice, this arrangement consistentlyachieves a longitudinal positioning of the associated vehicle axis atthe same point; to be precise, centrally above the wheel wells.Transversely to the conveying direction, the vehicles can be centeredexactly with the middle of the conveying line by means of thetransversely floating support of the vehicle wheels and by means of acentering mechanism engaging on the tire flanks by means of centeringedges and arranged so as to be countersunk in the floor of theworkstation.

By the vehicles being centered in the middle, a transverse positioningwhich is uniform, irrespective of the track width and wheel width, isachieved. Since the centering edges bear only on the tire flank, contactwith or damage to the rims is ruled out. By the vehicles beingpositioned according to the invention, a positional tolerance of thevehicles of approximately ±5 mm in the longitudinal and transversedirections can readily be achieved. So long as certain approximatefilling-pressure tolerances for all the tires are maintained, thisaccuracy is not impaired by varying air pressure in the tires. Due tothe rapid and accurate positioning of the vehicles conveyed into a newworkstation, the invention facilitates the use of automation techniquesin the ultimate phase of the final assembly of vehicles.

Where steerable axles are concerned, the centering edges shouldexpediently be mounted pivotably on the associated centering mechanism,so that the centering edges can come to bear, without tilting, on thetire flanks; and, when the vehicle is being centered, no actioninvolving force is exerted on the vehicle steering. Differenttype-specific center distances are taken into account by means ofcorrespondingly long carrying rollers or floatingly mounted receivingsurfaces.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a vertical longitudinal section through a first exemplaryembodiment of a conveying apparatus for the intermittent conveyance ofvehicles rolling on their wheels in the region of a workstation, using adrag-chain conveyor;

FIG. 2 shows a vertical cross section through the conveying apparatusaccording to FIG. 1;

FIG. 3 shows a vertical longitudinal section through a workstation withan apparatus for the exact positioning of a vehicle rolling on itswheels, as a further exemplary embodiment;

FIG. 4 shows an illustration in horizontal projection of the apparatusat the workstation according to FIG. 3;

FIGS. 5 and 6 show a vertical cross section and a top view respectively,of a pair of wheel stand-on plates of a workstation with an associatedcentering mechanism, as a third exemplary embodiment;

FIG. 7 shows a vertical longitudinal section through a workstation withmeans for the positioning of vehicles, as a fourth exemplary embodiment;

FIG. 8 shows a vertical longitudinal section through a wheel well, theinclined flanks of which are designed in the form of pivotable flaps;

FIG. 9 shows an individual illustration of a further exemplaryembodiment of a centering mechanism for the central alignment of avehicle axle; and

FIG. 10 shows a further exemplary embodiment of the invention, using anapron conveyor with movable wheel wells and wheel stand-on platesintegrated into the composite articulated structure of the apronconveyor.

DETAILED DESCRIPTION OF THE DRAWINGS

In the exemplary embodiments illustrated, the invention is shown in twodifferent basic versions which differ from one another in the nature ofthe conveying lines 12 and 12′ below the vehicle wheels 5. On the onehand, several exemplary embodiments are illustrated, which show (FIGS. 1and 2) or presuppose (FIGS. 3 to 8) a drag-chain conveyance of thevehicles. In the drag-chain conveyance of the vehicles, one of theconveying lines 12 is designed as a rolling track 9, supplemented by adrag-chain conveyor 13, 14, 23, whereas there is no conveying lineprovided on the other side of the vehicle, but merely a rolling track 9.The vehicle wheels can roll freely on the rolling tracks 9. Here, thewheel wells and wheel stand-on plates are assigned to the individualworkstations 11 in a stationary manner.

In the exemplary embodiment according to FIG. 10, the conveying linesbelow the vehicle wheels on each side of the vehicle are designed ineach case as apron conveyors. The vehicle wheels stand on wheel wells 36or wheel stand-on plates 37 which are integrated into the compositearticulated structure of the movable apron conveyors. By the apronconveyors being stopped in the correct position, after each conveyingstroke the wheel wells 36 and wheel stand-on plates 37 are in each caserepositioned at the individual workstations 11′.

The exemplary embodiments with drag-chain conveyance will be dealt within more detail first, one of which is shown in a more comprehensiveillustration in FIGS. 1 and 2. This is, in general terms, an apparatusfor the intermittent conveyance and positioning of vehicles 1 rolling ontheir own wheels 5 along a production line 10 which, in the exemplaryembodiment illustrated, comprises a workstation 11. The vehicles on theproduction line jointly execute a conveying stroke corresponding to thedistance between stations by means of the conveying lines and arestopped again and positioned in order to carry out work. For thispurpose, two rolling tracks 9 for the vehicle wheels 5 are provided nextto one another in parallel and are arranged at a distance correspondingto the gauge of the vehicles 1.

One rolling track is assigned a pair of drag chains 13 which are laid inan endless loop over deflecting wheels 23 and are driven in theconveying direction X. The pair of drag chains is laid with its upperstrand following the rolling track being near the floor. Moreover, thedrag chains are provided with a plurality of drivers 14, which can bepositioned to apply a thrust against the circumference of a vehicle tire5 of a vehicle 1 to be conveyed. The drivers may be designed as a tripleset of parallel rollers or cylinders which touch one another and arerotatably mounted and of which one roller rolls on the rolling track andthe other two roll on the tire circumference.

So that vehicles of different types which roll on their own wheels canbe exactly and efficiently positioned and aligned automation-compatiblyand type-flexibly within a workstation 11 of the production line in theconveying direction X and in the transverse direction Y, a package ofmeasures is provided according to the invention.

A prismatic center-symmetrical wheel well 15′ with a center line 31 isarranged in each case in each rolling track 9 in the region of theworkstations 11. Several exemplary embodiments of wheel wells arepresented in more detail below. The wheel wells are orientedtransversely to the conveying direction X and are arranged in the sameposition relative to one another, with respect to the conveyingdirection, in the rolling tracks 12. They are arranged in a stationarymanner within the workstation 11 according to the desired position ofthe vehicle 1 or of the respective vehicle axle 2, 3. The wheel wellsare shaped, in cross section, such that variously sized vehicle tires 5of all the vehicle types occurring in the production line 10 can bereceived in them in a positionally accurate manner. In all the exemplaryembodiments, the wheel wells are designed in such a way that the vehicletire 5 of the vehicle wheel received in them is supported displaceablyin the transverse direction Y.

Furthermore, wheel stand-on supports 21 are provided in the rollingtracks 9 at a longitudinal distance from the wheel wells whichcorresponds to the center distance A of the vehicles. (See FIG. 3.) Thesupports are formed by a set of parallel carrying rollers 22 orientedwith their axes of rotation in the conveying direction X (FIGS. 3 and 4or FIGS. 5 and 6). Alternatively, the wheel stand-on supports 21′ mayalso be designed as a transversely floatingly guided plate (FIG. 1 or7). The wheel stand-on supports 21, 21′ cover the various centerdistances A of all the vehicle types occurring in the production line10. In the exemplary embodiments illustrated, this is achieved, despitethe wheel stand-on supports' being arranged at a fixed location, in thatthey are dimensioned (dimension L) to be longer in the conveyingdirection X than the sum of the wheel stand-on area and the difference Dbetween the largest and smallest center distance A occurring.

So that all the gauges S and wheel widths b of all the vehicle typesoccurring in the production line 10 can also be covered, the width,measured in the transverse direction Y, of the rolling tracks 9, thewidth B of the wheel wells and the width of the wheel stand-on platesare in each case dimensioned, taking into account their mutualtransverse distance, such that said elements, despite being arranged ata fixed location in the workstations, can readily cover the occurring orpossible range of gauges and tire widths.

For centering, each two opposite wheel wells and two wheel stand-onsupports of each workstation 11 is assigned a pair of movably guidedlongitudinally oriented centering edges 25 and 25′ which project beyondthe rolling level of the rolling tracks 9. These edges can be laidagainst mirror-symmetrical flanks 6 of the vehicle tires 5 of a vehiclereceived at the workstation. (What is illustrated is a situation wherethe centering edges come to bear on the inside, which is expedient forreasons of space.) For this purpose, the centering edges 25 and 25′ arearranged in each case at a mutual transverse distance such that they canbe laid in a centering manner against the inside tire flanks 6 and canbe moved outwards away from the middle 24 for centering the vehiclewheels 5. The centering edges 25 assigned to the wheel stand-on platesare connected immovably to the associated centering mechanism, which isdealt with in more detail below. Moreover, the centering edges 25assigned to the wheel stand-on plates are approximately as long as thewheel stand-on plates (dimension L) . The height of the centering edgesis selected such that, even in the case of low-section tires, they donot come into contact with the rim of the vehicle wheel, so that damagecannot occur there.

The non-steerable wheels are accurately aligned in the conveyingdirection X, apart from a slight skew position of the vehicle on therolling tracks which, incidentally, is to be eliminated. By contrast,the centering edges 25′ assigned to the steerable vehicle axle 2 areheld on the associated centering mechanism 26 so as to be pivotableabout a vertical pivot axis 27, so that, when the steerable vehiclewheels are standing obliquely, the centering edges do not come to bearagainst the tire flanks in an angular way, but can automatically fitsnugly onto the tire flank. Incorrect positioning can thereby beavoided. As seen in horizontal projection, the pivot axis 27 is arrangedapproximately at the position of the transversely running center line 4of the steerable vehicle axle 2 of the vehicle 1 received in position.

Provided in each case in the drive for moving each pair of centeringedges 25, 25′ is a centering mechanism which is described below inseveral exemplary embodiments. By means of the centering mechanism, thetwo opposite centering edges can be moved transversely, (that is, in thedirection Y) positively in synchronism and mirror-symmetrically inrelation to the center line 24 of the production line 10, and, by meansof the said centering mechanism, the vehicle can be oriented via thetires symmetrically and parallel to the center line 24 of the productionline.

Before the procedure for positioning the conveyed vehicles is dealt within more detail, further particulars of the exemplary embodiments whichare relevant to the positioning sequence will be described beforehand.

As already mentioned, there are various possibilities for theconfiguration of the wheel wells. In principle, they are designed with aprismatic cross section and symmetrically with a horizontal bottom andinclined flanks. The differences are attributable to whether the wheelload is absorbed by the two inclined well flanks 16 or by the horizontalbottom 17.

In the exemplary embodiment of the wheel wells 15 which is illustratedin FIGS. 3 and 4, the inclined flanks 16 absorb the wheel load. Theflanks are accordingly arranged immovably with respect to theirinclination and/or the distance between them. So that the vehicle wheelreceived therein can easily be displaced, and the vehicle thus centered,in the Y direction the inclined flanks 16 are formed by a set ofparallel carrying rollers 18, of which the axes of rotation, as seen inhorizontal projection, are oriented parallel to the conveying directionX. On the one hand, as large a number of carrying rollers as possibleshould be provided, so that the wheel received in the wheel well caneasily be displaced on them. This entails a short distance between themand therefore also a small diameter of the carrying rollers. On theother hand, for reasons of sufficient stability, the carrying rollerscannot be made as small as might otherwise be desired. A practicablecompromise must therefore be made.

Instead of the inclined flanks of the wheel wells absorbing the wheelload being designed in the form of a set of carrying rollers, it is alsopossible for the well flanks to be designed as transversely floatinglyguided plates. These are steel plates which are provided at theirtransverse lateral margins, on the underside, with dust-protected linearrolling-bearing guides which, on the one hand, allow easily movingtransverse guidance of the wheel received and, on the other hand, makeit possible to have a stand-on surface, continuous over a large area,for the tire (so-called tire contact area) on the inclined plates. Sothat, after a vehicle wheel is newly placed onto a transverselyfloatingly mounted plate, there is sufficient clearance for movement tothe right and to the left for positioning in the transverse direction,each plate is equipped with a centering spring which, after beingrelieved, returns the floatingly mounted plate into a middle position.In this manner, a wheel can always be placed onto a plate which is inthe middle position within a clearance for its movement.

The exemplary embodiment, shown in FIGS. 3 and 4, of a pair of oppositewheel wells with immovably arranged flanks 16 absorbing the wheel loadhas the advantage that the tires of a respective vehicle axle areautomatically positioned in the longitudinal direction X after thevehicle axle has rolled into the two opposite wheel wells, withoutfurther activity. One disadvantage is some unevenness of the rollingtracks in the region of the wheel wells, which may, under certaincircumstances, disrupt a jolt-free transportation of the successivevehicles conveyed by the drag chain. As regards the design of the wheelwells according to FIGS. 3 and 4, after the vehicle is positioned in thelongitudinal direction X after the respective vehicle axle has rolledinto the associated wheel well, it merely needs to be oriented andcentered in the transverse direction Y parallel to and symmetrically tothe center line 24 of the workstation by the actuation of the centeringmechanism and by the centering edges coming to bear against the innerlateral flanks. Where the wheel wells according to FIGS. 3 and 4 areconcerned, therefore, positioning of the vehicle takes place first inthe longitudinal direction and then in the transverse direction.

In the exemplary embodiment of the wheel well 15″ as shown in FIG. 7,the flanks are movable as regards the distance between them. In thiswheel well, the wheel load is absorbed by the horizontal bottom 17 whichis designed as a transversely floatingly guided plate. The design ofsuch a plate is entirely similar to that which was described above inconnection with the other wheel well according to FIGS. 3 and 4. Thewell flanks do not absorb any wheel load here, but, at most, forces forpositioning the vehicle wheel into the desired position. Here,therefore, the well flanks are designed displaceably and, in theexemplary embodiment according to FIG. 7, as a pair of strips or wedges19 of triangular cross section, which, after the vehicle wheel has cometo a stop in the interspace between the wedges, are moved togetherpositively in synchronism and symmetrically in the direction of thearrows oriented parallel to the X-direction and, at the same time,position the vehicle wheel in the X-direction. While the vehicle isbeing transported into the approaching position, the wedges 19 areshifted out of the region of the rolling tracks, so that the wheels canroll over the wheel wells unimpeded. During the transportation of thevehicles, the two strip-like wedges 19 can be drawn away laterally outof the region of the rolling tracks, preferably towards the center 24.Because shorter movement strokes are involved, it seems more expedientfor the strip-like wedges 19 to be lowered below the rolling level ofthe rolling tracks into small recesses in front of and behind thefloating plate of the well bottom.

In order to position the vehicle in the workstation according to FIG. 7,because of the different design of the wheel wells the operation isopposite to that described further above in connection with FIGS. 3 and4. That is, the vehicle 1 dragged into the workstation is prepositionedthere only approximately in the longitudinal direction by the strip-likewedges 19 being raised in due time above the rolling level of therolling tracks. Specifically, the wedges 19 are raised exactly when theaxle assigned to the wheel well (here the non-steerable axle 3) has justreached the wheel well 15″. Subsequently, the approximatelyprepositioned vehicle is centered and oriented exactly in the transversedirection Y and only thereafter is fine-positioned in the longitudinaldirection X, in that the strip-like wedges 19 are moved together bymeans of a suitable centering mechanism in the direction of the arrowspositively in synchronism and symmetrically to the centering line of thewheel well. As a result, the vehicle wheels, which are initially onlyapproximately prepositioned in the wheel well 15″, are moved towards thecenter line 31 of the wheel well and are fixed accurately in positionthere. It also becomes clear, then, that in this type of wheel well itis more expedient for longitudinal positioning to be carried out lastbecause, after longitudinal positioning, the strip-like wedges 19 bearwith some prestress against the tire circumferences and transversedisplacement would subsequently be possible only with increasedresistance.

The further exemplary embodiment of a wheel well 15, as illustratedindividually in FIG. 8, likewise follows the principle of the wheel well15″ according to FIG. 7, in which the wheel load is absorbed by thebottom 17 of the wheel well 15. Here, however, the bottom is formed by aset of parallel carrying rollers 18′, the axes of rotation of which areoriented parallel to the conveying direction. The vehicle can therebyeasily be centered in the Y-direction. Here, the well flanks arevariable in terms of their inclination and are formed by a pair ofpivotable flaps 20 which can be moved together by means of a mechanism(not shown) likewise positively in synchronism and symmetrically in thedirection of the pivoting arrows, the vehicle wheel being positioned inthe X-direction. During the transportation of the vehicles, thepivotable flaps 20 can be lowered, flush with the surface, to the levelof the rolling tracks. The procedure for positioning a vehicle which hasmoved into the associated workstation is entirely similar to thesequence outlined in connection with FIG. 7.

Expediently, the pivotable centering edges 25′ are assigned to the wheelwells, which means that the vehicle is positioned in the longitudinaldirection X via the wheels of the steerable vehicle axle. To be precise,if, as seen in horizontal projection, the pivot axes 27 of the centeringedges are arranged at the position of the transversely running centerline of the wheel wells, this arrangement can ensure in the simplest andmost effective way possible that these pivot axes also lie at theposition of the center line of the steerable vehicle wheels, which isimportant for an operationally reliable and accurate centering of thevehicle axle.

The centering edges of the centering mechanism assigned to the steerablevehicle axle 2 should not execute any movement to the longitudinaldirection during centering, because this may react on the steering ofthe wheels, on their steering-lock position and on the centeringaccuracy, which is undesirable. The pivotable centering edges must bemoved along a straight line which, as seen in horizontal projection,runs transversely to the conveying direction. The associated centeringmechanism is therefore provided with a transversely oriented straightguide 28 for the part which carries the pivot axes 27 of the associatedcentering edges 25′.

By the vehicles being positioned according to the invention, they arepositioned with sufficient accuracy in the longitudinal and transversedirections, so that some jobs (for example the application of protectivefilm) can be readily automated. Due to air-pressure differences in thetires and because of different suspension compression states, anaccurately reproducible positioning of the body with regard to thevertical direction cannot be carried out with the same accuracy. Shouldthe automation of other jobs necessitate or presuppose an exact verticalpositioning and/or an even more accurate longitudinal and transversepositioning than is possible according to the invention, then amechanical apparatus must be provided at the respective workstation,which moves with centering journals into the body-side jack bushes andat the same time orients and positions the vehicle even more accuratelyin respect of all three spatial directions. Due to the sufficientlyaccurate positioning of the vehicle by means of the apparatus accordingto the invention, this even more accurate positioning of the vehicle canbe brought about very quickly. In this case, the vehicle is alsoreliably fixed mechanically and cannot yield in an uncontrolled mannerwhen forces are exerted on the vehicle as a result of the productionoperation. This additional positioning and fixing unit must be coupledfunctionally in control terms to the conveying lines and the positioningunits, in such a way that the additional positioning and fixing unit isthe last of the units mentioned to fix the body after a conveying strokeand is the first to release the body again after the end of the work andbefore a new conveying stroke.

The other basic version of the invention, as illustrated in FIG. 10,will be referred to below. A pair of apron conveyors 32 is provided asconveying lines 12′ for conveying the vehicles 1 through the productionline from workstation 11′ to workstation. The individual apron conveyorsare composed of a multiplicity of individual plates 35 which areconnected to one another in a hinge-like manner via joints 38. Theplates interconnected in the manner of a chain are laid over deflectingwheels in an endless closed loop which can be driven in the conveyingdirection via one of the deflecting wheels. That strand of the apronconveyor which is moved through the production line in the conveyingdirection is laid approximately flush with the surface of the work floorwith respect to the top side of the plates. For this purpose, in theexemplary embodiment illustrated, a guide channel 33, the base of whichforms a guide rail 34, is introduced into the work floor. The supportingrollers 39 of the individual plates can roll, with insignificantresistance, on this guide rail and nevertheless at the same time absorbhigh carrying loads.

According to the invention, a plurality of wheel wells 36 and wheelstand-on plates 37 are integrated in each case into the right-hand andthe left-hand composite articulated structure of the apron conveyors 32and are moved jointly with the apron conveyors from workstation 11′ toworkstation. The wheel wells 36 and the wheel stand-on plates 37correspond, in their function and operation, to the embodiment shown inFIG. 3 and described with reference to the illustration there, so thatreference may be made to that extent to the statements made above. Aprecondition for integrating the wheel wells and the wheel standonplates into the composite articulated structure of the apron conveyorsis that the distances between the workstations along the respectiveproduction line and the distances between the wheel wells within thecomposite articulated structure of the apron conveyors correspond to acommon grid arrangement. In the simplest instance, the workstations arearranged equidistantly within the production line and the distancesbetween the wheel wells succeeding one another in the compositearticulated structure are identical to the distances between stations.At a distance corresponding approximately to the center distance A ofthe vehicles, a wheel stand-on plate 37 is integrated, behind each wheelwell 36, into the composite articulated structure. Both the wheel wells36 and the wheel stand-on plates 37, like the other plates 35 of thecomposite articulated structure, too, are supported movably on the guide34 of the apron conveyors 32 by means of supporting rollers 39.

During the entire run through the production line, a vehicle placedeither in a pair of wheel wells or on a pair of wheel stand-on plates ofthe apron conveyors 32 remains standing on these wheel wells and wheelstand-on plates. A relative displacement of the vehicles in theconveying direction X in relation to the apron conveyors is not possiblebecause of the wheel wells. For positioning the vehicles conveyed on theapron conveyors in the X-direction at the associated workstations, thedrive of the apron conveyors is stopped exactly in position.

When the apron conveyors are new and not yet worn, good positioningaccuracy is thereby achieved for all workstations. With an increasingage of the apron conveyors, however, wear occurs in the joints 38 of thecomposite articulated structure and on the driving wheels and, as itaccumulates over the large number of points of articulation, may lead togreater tolerances in positioning. To avoid such inaccuracies, at eachworkstation 11′ there is provided in each case an interlocking device,by means of which the wheel wells 36 integrated into the rotatingcomposite articulated structure are not only in each case automaticallyinterlocked mechanically, but can also be accurately positioned in theconveying direction X beforehand. As a result, positioning errors causedby wear or due to errors in the spacing of the individual members 35 ordriving wheels can be compensated and eliminated.

For this purpose, an interlocking pin 40 is provided in the floor ofeach workstation, below the two guide rails 34 for the apron conveyors,and, in the exemplary embodiment illustrated, is guided verticallymovably in a fixed guide bush. The said interlocking pin can be moved byremote control, for example, by means of an actuating magnet 41. Otheractuating mechanisms and power assistances, such as, for example,pneumatics or hydraulics, may, of course, also be envisaged.

An interlocking orifice 42 for the low-play reception of theinterlocking pin is provided on the underside in each wheel well 36. Sothat the interlocking pin can find the well-side orifice reliably evenin a somewhat incorrect position, the interlocking pin 40 is designedconically on the end face, so that, when pressed axially against themargin of the interlocking orifice, it forces the wheel well into thecorrect position, in which the pin 40 and the orifice 42 are inalignment with one another. The wheel well is automatically forced intothe correct longitudinal position as a result of this operation. Sinceany misalignment of the wheel well with respect to the transversedirection does not need to be corrected, the interlocking pin 40expediently has a rectangular cross section and the interlocking orificeis designed as a long hole extending in the transverse direction, onlythose dimensions of the pin 40 and orifice 42 which lie in the conveyingdirection X matching with one another, and considerable play existingbetween the two in the transverse direction Y.

As soon as the apron conveyors have come to a standstill after aconveying stroke of the vehicles standing on them, all the interlockingpins on the production line are moved out of the lowered releaseposition, illustrated by broken lines, into the raised interlockingposition, illustrated by unbroken lines, in which they also remainduring the entire production phase. To move the apron conveyors 32farther along, the interlocking pins of all workstations 11′ are jointlyunlocked by remote actuation.

So that the apron conveyors 32 can readily be moved beyond the necessarydeflecting wheels in spite of the wheel stand-on plates 37 integratedinto the rotating composite articulated structure and/or of theintegrated wheel wells 36, in the exemplary embodiment illustrated thewheel stand-on plates 37 and the wheel wells 36 are in each case ofmulti-part design. The carrying rollers of the wheel stand-on plates arealso divided correspondingly. The individual parts 37′, 37″ of the wheelstand-on plate and the parts 36′, 36″ of the divided wheel well areconnected to one another in a hinge-like manner by means of joints 38 inthe same way as the individual plates 35 of the apron conveyors 32.

The centering mechanisms 26, 26′, 26″ for centering and orienting thevehicles parallel to and symmetrically to the center line of theworkstation, the said centering mechanisms being shown in variousexemplary embodiments in FIG. 4, in FIGS. 5 and 6 and in FIG. 9, will bedealt with in more detail below. One centering mechanism is provided foreach vehicle axle 2 and 3; that is, two centering mechanisms areprovided in each workstation 11, 11′. The centering mechanisms arearranged in a stationary manner in the workstations 11 and 11′ in bothbasic versions mentioned (FIGS. 1 to 8 and FIG. 10).

All the centering mechanisms are based in an identical way on a guidemember 43, 43′ or 43 a/43 b which is mounted centrally at the positionof the center line 24 of the workstation. Two identical kinematicpart-gears are built up on these guide members in different directionsand are designed symmetrically to one another, each of them carrying acentering edge 25 or 25′ on its output member. The two associatedkinematic part-gears are coupled positively to one another via thecentral guide member, in such a way that the two part-gears can executeonly movements of equal dimension, but directed opposite to one another.Specifically, the symmetrical movement of the two part-gears isirrespective of whether a force setting the part-gears in motion isintroduced asymmetrically into one of the part-gears or whether it iscentrally introduced symmetrically. The symmetry of movement of the twopart-gears is also irrespective of whether the resistances to beovercome by the output members of the two part-gears are equal or differgreatly.

In the two centering mechanisms 26 illustrated in FIG. 4, the centralguide member 43 is designed as a guide bolt which is guided axiallymovably parallel to the center line 24. By the guide journal beingconnected to the piston rod of a drive cylinder 44, the guide journal iscapable of being driven at the same time pneumatically or hydraulicallyin the axial direction. Fastened with a vertical pivot axis to the guidejournal is a joint, to which are secured in an articulated manner twobuckle-proof connecting rods 45 of equal length which extendsymmetrically away from the center line on different sides. The otherend of each connecting rods is articulated to a lifting journal 46 whichis linearly guided transversely to the center line 24 and which, inturn, is mounted axially movably in a straight guide approximatelycentrally below the wheel well 15 or the wheel stand-on plate 21.Finally, each lifting journal 46 carries a centering edge 25 or 25′. Bydisplaying the guide journal 43 longitudinally in one direction or theother by means of the drive cylinder 44, the two associated liftingjournals 46 and, with them the centering edges 25, 25′, can be displacedsymmetrically in the transverse direction.

In the two exemplary embodiments of a centering mechanism 26′ which areillustrated in FIGS. 5 and 6, the central guide member 43′ is designedas a bearing journal of a rotatably mounted gearwheel pinion 30 which isfixedly mounted in the same position with respect to the center line 24,the mounting being arranged, as seen in the longitudinal direction,approximately centrally below the wheel well or the wheel stand-on plate21. Racks 29 engage at diametrical circumferential points of thegearwheel pinion 30 into the toothing (not shown) of the pinion.

Instead of a toothing or mutual tooth engagement, non-slip rollingbetween the rack 29 and the fixedly mounted wheel 30 may also be ensuredby means of tautly tensioned rolling bands which are looped around thewheel 30 in opposite directions and are fastened at the ends to therolling surface of the rack 29. The two racks 29 engaging diametricallyon the wheel or gearwheel pinion 30 are guided transversely to thecenter line 24 and mounted axially movably in a linear straight guide.They carry on their ends the centering edges 25 which have already beenmentioned. The wheel or gearwheel pinion 30 rotatably mounted at a fixedlocation and its non-slip rolling engagement with the two racks 29ensure, in mechanical terms, that a movement introduced anywhere intoone of the connected parts is converted into two equal, but oppositelydirected movements of the two racks 29 and of the centering edges. Themovement drive for introducing such a movement is not illustrated in theexemplary embodiment of FIGS. 5 and 6. It is possible for the gearwheelpinion 30 to be driven by means of a suitable slow rotary drive havinglimited torque. It is also possible for one of the racks 29 to bepneumatically or hydraulically driven linearly by means of a drivecylinder. Racks 29 engage at diametrical circumferential points of thegearwheel pinion 30 into the toothing (not shown) of the pinion.

Instead of a toothing or mutual tooth engagement, non-slip rollingbetween the rack 29 and the fixedly mounted wheel 30 may also be ensuredby means of tautly tensioned rolling bands which are looped around thewheel 30 in opposite directions and are fastened at the ends to therolling surface of the rack 29. The two racks 29 engaging diametricallyon the wheel or gearwheel pinion 30 are guided transversely to thecenter line 24 and mounted axially movably in a linear straight guide.They carry on their ends the centering edges 25 which have already beenmentioned. The wheel or gearwheel pinion 30 rotatably mounted at a fixedlocation and its non-slip rolling engagement with the two racks 29ensure, in mechanical terms, that a movement introduced anywhere intoone of the connected parts is converted into two equal, but oppositelydirected movements of the two racks 29 and of the centering edges. Themovement drive for introducing such a movement is not illustrated in theexemplary embodiment of FIGS. 5 and 6. It is possible for the gearwheelpinion 30 to be driven by means of a suitable slow rotary drive havinglimited torque. It is also possible for one of the racks 29 to bepneumatically or hydraulically driven linearly by means of a drivecylinder.

In the exemplary embodiment of a centering mechanism 26″, as illustratedindividually in FIG. 9, the central guide member has a multi-partdesign. To conform to the generally diamond-shaped design of the twoassociated kinematic part-gears, which are formed from four articulatedbuckle-proof connecting rods 47 of equal length, two diametricallyopposite corner joints must be fixed on the center line. For thispurpose, on the one hand, a fixed bearing 43 a and, on the other hand, abearing 43 b guided longitudinally movably are provided. Because twocorner points of the diamond-shaped four-bar linkage are fixedcentrally, the other two corner points move to the same extent, butopposite to one another, in the transverse direction Y. The centeringedges 25 are articulated at these two corner points of the four-barlinkage. So that the centering edges cannot be pivoted, but are movedonly parallel to one another (as is necessary in the case of the vehicleaxles with non-steerable vehicle wheels), two parallelogram links 48 arealso articulated on the centering edges, so as to be offset to theconnecting rods 47, and are fixedly mounted with the same offset on thecenter line. In this exemplary embodiment, the drive cylinder 44′engages directly on the two opposite centering edges. The centeringmechanism described no longer needs, here, to convert the drive movementinto an output movement, but merely has to ensure that the movementintroduced is distributed uniformly and symmetrically to the twoopposite centering edges. In this method of introducing the drivemovement, the centering mechanism is subjected to mechanical load onlywhen there are widely differing resistances on one side, as comparedwith the other.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

What is claimed is:
 1. Apparatus for the conveyance and positioning of avehicle which is supported on its own wheels along a production linehaving at least one workstation, said apparatus comprising: for thevehicle wheels, first and second conveying lines arranged adjacent aproduction line floor, parallel to one another, at a distancecorresponding to a gauge of the vehicles, by means of which the vehiclecan be conveyed through the production line; a prismatic shaped wheelwell oriented transversely to a conveying direction of the vehicle ineach of the conveying lines in a region of a workstation, said wheelwells being arranged in the conveying lines, within the workstation, inan identical position to one another and according to a desired positionof the vehicle or of its axle, and being shaped, in cross section, suchthat variously sized vehicle tires can be received and supported in anexact predetermined position therein relative to the conveying directionof the vehicle, with the vehicle tire supported displaceably in thetransverse direction relative to the conveying direction; and a wheelsupport arranged in each of the conveying lines at a distance betweenthe vehicle axles from the wheel wells, the wheel support comprising oneof a transversely movable plate and a set of parallel carrying rollersoriented with the axes of rotation in the conveying direction; whereinthe wheel supports are longer in the conveying direction than the sum ofthe length of a stand-on area of the tire plus at least the differencebetween the largest and smallest possible center distances; the widthtransversely to the conveying direction of the wheel wells and of thewheel supports are dimensioned, taking into account their mutualtransverse distance, to accommodate differing gauges and tire widths ofall the vehicle types occurring in the production line; in eachworkstation, both the two wheel wells belonging thereto and twoassociated wheel supports have a pair of movably guided centering edgeswhich project above the conveying lines and which can be laid againstmirror-symmetrical sides of the two vehicle tires of a vehicle axlereceived in the wheel wells or standing on the wheel stand-on plates;and a movement drive of each pair of centering edges has a centeringmechanism, by means of which the two centering edges located oppositeone another in pairs can be moved transversely to the conveyingdirection, positively in synchronism and symmetrically to the centerline of the production line.
 2. The apparatus according to claim 1,wherein at least one of the two conveying lines comprises a drag-chainconveyor; the drag-chain conveyor has a pair of drag chains which arearranged in a respective endless loop parallel to one another at adistance greater than a maximum wheel width, so as to follow, near thefloor, a rolling track for the vehicle wheels, and are driven in theconveying direction; the drag chains of the drag-chain conveyor areprovided with a plurality of drivers, each of which can apply a thrustto the tire circumference of a vehicle wheel of a conveyed vehicle; anyconveying line that is not a drag-chain conveyor, it comprises rollingtrack for the vehicle wheels of the corresponding vehicle side; and eachworkstation of the production line has an associated set of twostationary wheel wells and two wheel stand-on plates (21, 21′).
 3. Theapparatus according to claim 1, wherein the centering edges assigned tothe steerable vehicle axle are held on the centering mechanism (26)pivotably about a vertical pivot axis, the said pivot axis beingarranged, as seen in horizontal projection, approximately at theposition of a transversely running center line of the steerable vehicleaxle of the vehicle.
 4. The apparatus according to claim 3, wherein thecentering edges pivotable about a vertical pivot axis are assigned tothe wheel wells, the pivot axes being arranged, as seen in horizontalprojection, approximately at the position of the transversely runningcenter line of the wheel wells.
 5. The apparatus according to claim 3,wherein at least the centering mechanism assigned to the steerablevehicle axle has a straight guide for the part carrying pivot axes ofthe associated centering edges, such that during a transverse movementof opposite centering edges, the pivot axes are movable along a straightline which, as seen in horizontal projection, runs transversely to theconveying direction.
 6. The apparatus according to claim 1, wherein thecentering edges assigned to the wheel stand-on plates are approximatelyas long as the wheel stand-on plates.
 7. The apparatus according toclaim 1, wherein the centering edges assigned to the wheel stand-onplates are connected immovably to the associated centering mechanism. 8.The apparatus according to claim 1, wherein the centering edges arearranged at a mutual transverse distance such that they can be laid in acentering manner against the inner tire flanks and, for centering thevehicle wheels, can be moved outwards away from the center.
 9. Theapparatus according to claim 1, wherein the inclined flanks, absorbingthe wheel load, of the wheel wells are arranged immovably with respectto their inclination or their mutual distance, and comprise transverselyfloatingly guided plates or are formed by a set of parallel carryingrollers, of axes of rotation of which, as seen in horizontal projection,are oriented parallel to the conveying direction.
 10. The apparatusaccording to claim 1, wherein flanks of the wheel wells are movable withrespect to their inclination or to their mutual separation; and ahorizontal bottom of the wheel wells which absorbs the wheel load isdesigned as one of a transversely floatingly guided plate and a set ofparallel carrying rollers having axes of rotation oriented parallel tothe conveying direction.
 11. The apparatus according to claim 1, whereinthe two conveying lines carrying the vehicle wheels and conveying thevehicles through the production line are designed as one of slat andapron conveyors, and contain at uniform distance corresponding to adistance between successive workstations, so as to be integrated intothe rotating composite articulated structure of the slat or apronconveyors, a plurality of wheel wells supported movably on the guide ofthe slat or apron conveyors and a plurality of correspondingly movablysupported wheel stand-on plates.
 12. The apparatus according to claim11, wherein in a workstation, a device is provided for automaticmechanical interlocking and exact positioning of the wheel wells whichare integrated into the rotating composite articulated structure of theslat or apron conveyors and are capable of being moved on the conveyorguide and which, when the slat or apron conveyors move farther on, arecapable of being unlocked by remote actuation jointly for allworkstations.
 13. The apparatus according to claim 11, wherein the wheelsupports integrated into the rotating composite articulated structure ofthe slat or apron conveyors or the integrated wheel wells are in eachcase of multi-part design, the individual parts of each wheel support orof each divided wheel well being connected to one another in anarticulated manner in the same way as the individual plates or theindividual slats of the apron or slat conveyors.
 14. The apparatusaccording to claim 1, wherein in a workstation, an apparatus for themechanical fixing of the body of the positioned vehicle is provided, thesaid device having centering pins which move axially into body-side jackbushes and thereby position the vehicle body even more accurately withrespect to all three spatial directions.